Predictors of survival after cardiac or respiratory arrest in critical care units

Abstract

Background: Survival outcomes after cardiac or respiratory arrest occurring outside of intensive care units (ICUs) has been well described. We investigated survival outcomes of adults whose arrest occurred in ICUs and determined predictors of decreased survival.

Methods: We reviewed all records of adults who experienced cardiac or respiratory arrest from Jan. 1, 2000, to Apr. 30, 2005, in ICUs at four hospitals serving Edmonton, Alberta. We evaluated patient and clinical characteristics, as well as survival outcomes during a five-year follow-up period. We determined risk factors for immediate (within 24 hours) and later death.

Results: Of the 517 patients included in the study, 59.6% were able to be resuscitated, 30.4% survived to discharge from ICU, 26.9% survived to discharge from hospital, 24.3% survived to one year, and 15.9% survived to five years. Pulseless electrical activity or asystole was the most common rhythm (45.8% of the arrests). Survival was lowest among patients with an arrest due to pulseless electrical activity or asystole: only 10.6% survived to one year, compared with 36.3% who had other arrest rhythms (p < 0.001). Independent predictors of decreased later survival (eight months or more after arrest) were increasing age (adjusted hazard ratio [HR] 1.06, 95% confidence interval [CI] 1.03-1.09) and longer duration of cardiopulmonary resuscitation (CPR) (adjusted HR 1.38, 95% CI 1.03-1.83, per additional logarithm of a minute of CPR).

Interpretation: Our study showed no major improvement in survival following cardiac arrest with pulseless electrical activity or asystole as the presenting rhythm in the ICU despite many advances in critical care over the previous two decades. The independent predictors of death within 24 hours after arrest in an ICU were sex, the presenting rhythm and the duration of CPR. Predictors of later death (eight months or more after arrest) were age and duration of CPR.

Figure 1:

Top panel: Association between severity of illness (as measured by APACHE II score) and survival to hospital discharge among 251 patients with available APACHE II scores who had cardiac or respiratory arrest in an intensive care unit, by type of arrest. Bottom panel: Association between duration of cardiopulmonary resuscitation (CPR) and survival to hospital discharge among 516 patients with available data on duration of CPR who had cardiac or respiratory arrest in an ICU, by type of arrest.

Figure 2:

Kaplan–Meier curves for survival among 258 patients who were alive 24 hours after cardiac or respiratory arrest in an intensive care unit, by type of arrest.